diff --git a/du1/program.c b/du1/program.c
new file mode 100644
index 0000000..5e61b41
--- /dev/null
+++ b/du1/program.c
@@ -0,0 +1,32 @@
+#include<stdio.h>
+#include<stdlib.h>
+
+void printCharacter(int c);
+
+int main() {
+    int lineCount = 0;
+    int c;
+    char outChar;
+
+    while((c = getchar()) != EOF) {
+        if (c >= 'a' && c <= 'z') {
+            outChar = c - 'a' + 'A';
+        } else if (c >= 'A' && c <= 'Z') {
+            outChar = c - 'A' + 'a';
+        } else {
+            if (c == '\n') {
+                lineCount++;
+            }
+
+            outChar = c;
+        }
+
+        printCharacter(outChar);
+    }
+
+    printf("\nPočet riadkov: %d\n", lineCount);
+}
+
+void printCharacter(int c) {
+    printf("%c", c);
+}